Conventionally, an articulated robot arm mechanism is used in various fields such as an industrial robot. For example, the articulated robot arm mechanism like this is provided with a linear extension and retraction joint in combination with other joints. An arm section constituting the linear extension and retraction joint includes, for example, connection piece strings in each of which a plurality of pieces having the same shapes are connected in a string shape. The connection piece strings are joined, and thereby a columnar body having a certain rigidity is formed. When the linear extension and retraction joint is driven, the arm section extends or retracts. Specifically, when a motor rotates, the connection piece strings which are stored are guided to a joining mechanism, and the arm section as the columnar body formed by the connection piece strings being joined by the joining mechanism is extended. Accordingly, if the connection piece strings are moved out of a designed path, an extension and retraction motion of the robot arm mechanism is unlikely to be stable.